Current Splitter For LED Lighting System

ABSTRACT

Systems and methods for controlling a light emitting diode (LED) system having a plurality of LED arrays are provided. The lighting system can include a dimmable LED driver circuit configured to provide a driver output suitable for providing a driver current to the LED arrays. A current splitter circuit can be provided between the LED driver circuit and the plurality of LED arrays to control the ratio of current from the driver output provided to each of the plurality of LED arrays. The current splitter circuit can be configured to control the current ratio provided to the plurality of LED arrays independently of the driver output according to a current ratio control curve based at least in part on a variable reference signal provided at the current splitter circuit.

PRIORITY CLAIM

The present application claims the benefit of priority of U.S.Provisional Patent Application No. 62/085,980, entitled “CurrentSplitter for LED Lighting System,” filed Dec. 1, 2014, which isincorporated herein by reference for all purposes.

FIELD

The present disclosure relates generally to light emitting diode (LED)lighting systems, and more particularly to a circuit for controllingmultiple LED arrays.

BACKGROUND

LED lighting systems can include one or more LED devices that becomeilluminated as a result of the movement of electrons through asemiconductor material. LED devices are becoming increasingly used inmany lighting applications and have been integrated into a variety ofproducts, such as light fixtures, indicator lights, flashlights, andother products. LED lighting systems can provide increased efficiency,life and durability, can produce less heat, and can provide otheradvantages relative to traditional incandescent and fluorescent lightingsystems. Moreover, the efficiency of LED lighting systems has increasedsuch that higher power can be provided at lower cost to the consumer.

LED devices can be associated with various color temperatures and/ordifferent monochromatic colors. The color temperature of an LED deviceprovides a measure of the color of light emitted by the LED device. Forinstance, the color temperature can refer to the temperature of an idealblack body radiator that radiates light of comparable hue to the LEDdevice. LED devices associated with higher color temperatures canprovide a more bluish color while LED devices associated with lowercolor temperatures can provide a more reddish color. Certain LEDlighting systems can include multiple LED arrays associated withdifferent color temperatures. The light emitted by the different LEDarrays can be controlled to provide a desired overall color output forthe lighting system.

For instance, LED lighting systems can include one or more LED drivercircuits that are used to convert input power from an AC power source toa suitable driver current for powering LED arrays having one or more LEDdevices. The color temperature of the LED lighting system can beadjusted by controlling the amount of light emitted by the LED arrays ofdiffering color temperatures. In some systems, the color temperature ofthe LED lighting system is controlled based on the driver output of thedriver circuit so that the color temperature of the lighting systemapproximates the behavior of an incandescent lighting system during, forinstance, dimming of the lighting system.

SUMMARY

Aspects and advantages of embodiments of the present disclosure will beset forth in part in the following description, or may be learned fromthe description, or may be learned through practice of the embodiments.

One example aspect of the present disclosure is directed to a lightemitting diode (LED) system. The system can include a first LED array, asecond LED array, and a dimmable driver circuit configured to provide adriver output. The system can further include a current splitter circuitconfigured to receive the driver output and to provide a first currentto the first LED array and a second current to the second LED array. Thesystem can further include an interface at the current splitter circuitconfigured to receive a variable reference signal. The current splittercircuit can be configured to control a current ratio of the firstcurrent and the second current independently of the driver outputaccording to a current ratio control curve. The current ratio controlcurve can specify the current ratio as a function of at least thevariable reference signal.

Other example aspects of the present disclosure are directed to systems,methods, apparatus, circuits, and electronic devices for controlling alighting system having a plurality of LED arrays.

These and other features, aspects and advantages of various embodimentswill become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the present disclosure and, together with thedescription, serve to explain the related principles.

BRIEF DESCRIPTION OF THE DRAWINGS

Detailed discussion of embodiments directed to one of ordinary skill inthe art are set forth in the specification, which makes reference to theappended figures, in which:

FIG. 1 depicts an example LED lighting system according to exampleembodiments of the present disclosure;

FIGS. 2-3 depict example control curves according to example embodimentsof the present disclosure;

FIG. 4 depicts a schematic of an example current splitter circuitaccording to example embodiments of the present disclosure;

FIG. 5 depicts a schematic of an example circuit for providing avariable reference signal to a current splitter circuit according toexample aspects of the present disclosure;

FIG. 6 depicts an example LED lighting system according to exampleembodiments of the present disclosure

FIG. 7 depicts an example LED lighting system according to exampleembodiments of the present disclosure;

FIG. 8 depicts an example LED lighting system according to exampleembodiments of the present disclosure; and

FIG. 9 depicts a flow diagram of an example method according to exampleembodiments of the present disclosure.

DETAILED DESCRIPTION

Reference now will be made in detail to embodiments, one or moreexamples of which are illustrated in the drawings. Each example isprovided by way of explanation of the embodiments, not limitation of thepresent disclosure. In fact, it will be apparent to those skilled in theart that various modifications and variations can be made to theembodiments without departing from the scope or spirit of the presentdisclosure. For instance, features illustrated or described as part ofone embodiment can be used with another embodiment to yield a stillfurther embodiment. Thus, it is intended that aspects of the presentdisclosure cover such modifications and variations.

Example aspects of the present disclosure are directed to controlling aplurality of LED arrays in an LED lighting system. As used herein, alighting system can include, but is not limited to, one or more of alighting circuit, light engine, one or more luminaires, one or morelighting fixtures, one or more lighting units, a plurality of lightingdevices arranged in an environment, a combination of any of theforegoing, or other lighting system. An LED lighting system can includea plurality of LED arrays. An LED array can include one or more LEDdevices. In certain embodiments, each LED array can be associated with adifferent color temperature, different brightness, different lightingdirection or other characteristic. The lighting system can include adriver circuit configured to provide a driver output suitable forproviding a driver current to the LED arrays. A current splitter circuitcan be provided between the dimmable driver circuit and the plurality ofLED arrays to control the ratio of current from the driver outputprovided to each of the plurality of LED arrays. The current ratio amongthe plurality LED arrays can be controlled to provide desired overalllighting effects for the LED system, such as to provide a desired colortemperature, brightness, increased uplighting and/or downlighting, orother suitable effects.

According to example aspects of the present disclosure, the lightingsystem can include a dimmable driver circuit configured to provide adriver output. The driver output can be a suitable driver current forpowering the plurality of LED arrays. The dimmable driver circuit caninclude one or more controls for adjusting the driver output of drivercircuit. For instance, the dimmable driver circuit can be a linedimmable driver circuit (e.g. a phase-cut dimmable driver, a Triacdimmer, trailing edge dimmer, etc.). The line dimmable driver circuitcan adjust the driver output by adjusting the power input to the drivercircuit from an AC power source or other power source.

In addition and/or in the alternative, the dimmable driver circuit caninclude a dimming control interface. The dimming control interface canbe configured to receive a dimming control signal used to facilitatedimming of the plurality of LED arrays. As the dimming control signal isadjusted, the driver output of the driver circuit can be modified tocollectively reduce or increase the lumen output and/or radiant flux ofthe plurality of LED arrays. The dimming control signal can be, forinstance, a 0V to 10V signal received from an external circuit, such asa dimmer circuit, smart interface control, potentiometer, Zener diodecircuit, or other device. As used herein, a 0V to 10V lighting controlsignal can vary from, for instance, 1V to 9V, 1V to 10V, 2V to 8V, 2V to9V, 2V, to 10V, 1V to 11V, or other suitable range between about 0V andabout 10V. Other suitable protocols can be used for the dimming controlsignal. For instance, the lighting control signal can be a digitaladdressable lighting interface (DALI) lighting control signal, digitalmultiplex (DMX) lighting control signal, or other control signal.

The lighting system can further include an interface (e.g. one or morecircuits, terminals, pins, contacts, conductors, etc.) at the currentsplitter circuit for receiving a variable reference signal used tocontrol the current ratio among the plurality of LED arrays. Similar tothe dimming control signal, the variable reference signal can be, forinstance, a 0V to 10V signal provided from an external circuit such as adimmer circuit, smart interface control, potentiometer, Zener diodecircuit, or other device. The lighting control signal can be a DALIlighting control signal, DMX lighting control signal, or other controlsignal. Alternatively and/or in addition, the current splitter circuitcan have its own internal variable reference for controlling the currentratio among the plurality of LED arrays.

The current splitter circuit can adjust the current ratio among theplurality of LED arrays based at least in part on the variable referencesignal independently of the driver output. For instance, the dimmabledriver circuit can be used to reduce or increase the driver outputprovided to the current splitter to control the overall lumen output ofthe plurality of LED arrays. The variable reference signal provided tothe current splitter circuit can be used to independently adjust thecurrent ratio among the plurality of LED arrays regardless of the driveroutput provided to the current splitter. The independent adjustment ofthe current ratio among the plurality of LED arrays can provide for theindependent color temperature adjustment and/or adjustment of otherlighting effects of the LED system.

For example, a lighting system can include a first LED array and asecond LED array. The first LED array can be associated with a differentcolor temperature relative to the second LED array. As the variablereference signal provided to the current splitter circuit is adjusted,for instance, from 0V to 10V, the current splitter circuit can adjustthe ratio of the current provided to the first LED array relative to thecurrent provided to the second LED array. As a result, the amount oflight emitted by the first LED array at a first color temperature can beadjusted relative to the amount of light emitted by the second LED arrayat a second color temperature, resulting in a different overall colortemperature of the light output of the lighting system.

As another example, a lighting system can include a first LED arrayassociated with a first lighting direction (e.g. to provide uplighting)and a second LED array associated with a second lighting direction (e.g.to provide downlighting). As the variable reference signal provided tothe current splitter circuit is adjusted, for instance, from 0V to 10V,the current splitter circuit can adjust the ratio of the currentprovided to the first LED array relative to the current provided to thesecond LED array. As a result, the amount of lighting in the firstdirection can be adjusted relative to the amount of lighting in thesecond direction to provide different lighting effects in the lightingsystem.

According to particular implementations, the current splitter circuitcan include one or more control devices, such as one or moremicrocontrollers, microprocessors, logic devices, integrated circuits,or other control devices. The control device(s) can be powered at leastin part by the driver output of the driver circuit and can receive as acontrol input the variable reference signal. The control device(s) cancontrol switching elements (e.g. transistors) in communication with eachof the plurality of LED arrays to respectively control the currentsupplied to each of the LED arrays.

The control device(s) can adjust the current ratio among the pluralityof LED arrays based at least in part on a current ratio control curveprogrammed in firmware or other memory accessible by the control device.The current ratio control curve can specify a ratio of currents amongthe plurality of LED arrays as a function of at least the variablereference signal. The current ratio control curve can take any suitableformat, such as a look table, matrix, or other data correlating currentratio with the variable reference signal.

The current ratio control curve can be easily defined in firmware orinstructions in memory accessible by the control device(s) according toconsumer needs to meet various optical output requirements. Forinstance, the current ratio control curve can be designed as linear,super-linear, parabolic, logarithmic, asymptotic, exponential, as a stepfunction, or other relationship between the current ratio and thevariable reference signal, depending on the desired performance of thelighting system. In this way, the current splitter circuit according toexample aspects of the present disclosure can be easily adapted to avariety of different lighting applications.

With reference now to the Figures, example embodiments of the presentdisclosure will be discussed in detail. FIG. 1 depicts an example LEDlighting system 100 according to example embodiments of the presentdisclosure. The LED lighting system 100 includes an LED driver module115, a current splitter module 125, and a plurality of LED arrays,including a first LED array 132 and a second LED 134. While two LEDarrays are illustrated in FIG. 1, those of ordinary skill in the art,using the disclosures provided herein, will understand that any numberof LED arrays can be used in the lighting system 100 without deviatingfrom the scope of the present disclosure.

Each of the first LED array 132 and the second LED array 134 can includeone or more LED devices. The LED devices can emit light (e.g. visiblelight, ultraviolet light, infrared light, or other light orelectromagnetic energy) as a result of electrons moving through asemiconductor material. In particular example implementations, the firstLED array 132 can be associated with a different color temperature thanthe second LED array 134. For instance, the first LED array can includeone or more LED devices that emit light at a different color than thesecond LED array.

The present disclosure is discussed with reference to LED arrays havingdifferent color temperature for purposes of illustration and discussion.The LED arrays can include many other suitable variations withoutdeviating from the scope of the present disclosure. For instance, theLED arrays can be associated with a different brightness, differentlighting direction, different layout, or other suitable characteristics.The LED arrays can be implemented on the same circuit board or ondifferent circuit boards.

The LED driver module 115 can include a dimmable driver circuit 110. Thecurrent splitter module 125 can include a current splitter circuit 120.In the embodiment illustrated in FIG. 1, the LED driver module 115 canbe disposed in a housing, circuit board, or other component of thelighting system 100 that is separate from and/or external to the currentsplitter module 125. For instance, the current splitter module 125 canbe a module external to the LED driver module 115 that is disposed in anelectrical path between the LED driver module 115 and the plurality ofLED arrays.

The dimmable driver circuit 110 can be configured to receive an inputpower, such as an input AC power or an input DC power, and can convertthe input power to a suitable driver output (e.g. driver current) forpowering the plurality of LED arrays. In some embodiments, the dimmabledriver circuit 110 can include various components, such as switchingelements (e.g. transistors) that are controlled to provide a suitabledriver output. For instance, in one embodiment, the driver circuit 110can include one or more transistors. Gate timing commands can beprovided to the one or more transistors to convert the input power to asuitable driver output using pulse width modulation techniques. In oneexample, the driver circuit 110 can convert the input power to a driveroutput that can range from about 0V to about 60V DC. As used herein, theuse of the term “about” in conjunction with a numerical value isintended to refer to within 25% of the stated numerical value.

In some example embodiments, the dimmable driver circuit 110 can be aline dimming driver, such as a phase-cut dimmable driver, Triac dimmer,trailing edge dimmer, or other line dimming driver. The driver outputcan be adjusted using the line dimming driver by controlling the inputpower to the dimmable driver circuit.

In addition and/or in the alternative, a first interface 140 can beprovided at the dimmable driver circuit 110 for receiving a dimmingcontrol signal used to control the driver output. The first interface140 can include one or more components for communicating the dimmingcontrol signal to the driver circuit 110. For example, the firstinterface 140 can include one or more circuits, terminals, pins,contacts, conductors, or other components for communicating the dimmingcontrol signal to the driver circuit 110.

The dimming control signal can be provided from an external circuit,such as an external dimming circuit. The external circuit can includeone or more devices, such as a smart dimming interface, a potentiometer,a Zener diode, or other device. In one example implementation, thedimming control signal can be a 0V to 10V dimming control signal,depending on the output of the external circuit. For instance, if a usermanually adjusts a dimmer, the dimming control signal can be adjustedfrom, for instance, 0V to 5V. The dimming control signal can beimplemented using other suitable protocols, such as a DALI protocol, ora DMX protocol.

The driver circuit 110 can be configured to adjust the driver outputbased at least in part on the dimming control signal. For example,reducing the dimming control signal by 50% can result in a correspondingreduction in the driver output of about 50%. The reduction of the driveroutput can reduce the overall driver current for supply to the pluralityof LED arrays. As a result, the lumen output of the plurality of LEDarrays can be simultaneously adjusted (e.g. dimmed) by varying thedimming control signal.

As illustrated in FIG. 1, the driver output can be provided to a currentsplitter circuit 120. The current splitter circuit 120 can be configuredto split the driver output into a first current for powering the firstLED array 132 and a second current for powering the second LED array134. In this way, the current splitter circuit 120 can be used to adjustthe lumen output of the first LED array 132 relative to the lumen outputof the second LED array 134. The current splitter circuit 120 can beconfigured to control the current ratio of the first current provided tothe first LED array 132 to the second current provided to the second LEDarray based on a variable reference signal (e.g. a 0V to 10V lightingcontrol signal).

More particularly, the lighting system 100 can include a secondinterface 150 at the current splitter circuit 120 for receiving thevariable reference signal. The second interface 150 can include one ormore components for communicating the variable reference signal to thecurrent splitter circuit 120. For example, the second interface 150 caninclude one or more circuits, terminals, pins, contacts, conductors, orother components for communicating a variable reference signal to thecurrent splitter circuit 120.

The variable reference signal can be provided from an external circuit,such as an external dimming circuit. The external circuit can includeone or more devices, such as a smart dimming interface, a potentiometer,a Zener diode, or other device. The variable reference signal can be a0V to 10V lighting control signal, depending on the output of theexternal circuit. If a user manually adjusts a dimmer, the variablereference signal can be adjusted from, for instance, 0V to 5V. Thevariable reference signal can be implemented using other suitableprotocols, such as a DALI protocol, or a DMX protocol.

In some example embodiments, the current splitter circuit 120 caninclude an internal circuit for providing an internal variable referencesignal. The internal circuit can be configured to provide, for instance,a 0V to 10V variable reference signal based at least in part on signalsreceived from a potentiometer, Zener diode, or other device directlycoupled to the internal circuit.

The current splitter circuit 120 can include one or more control devices(e.g. a microprocessor, a microcontroller, logic device, etc.) and oneor more switching elements (e.g. transistors) in line with each of thefirst LED array 132 and the second LED array 134. The control device(s)can control the amount of current provided to the first LED array 132and the second LED array 134 by controlling the switching elements. Theswitching elements used to control the amount of current provided to thefirst LED array 132 and to the second LED array 134 can be either on thelow voltage side of the LED arrays or the high voltage side of the LEDarrays.

In particular aspects, the control device(s) can control the currentprovided to the first LED array 132 and to the second LED array 134according to a current ratio control curve based on the variablereference signal. The current ratio control curve can be stored infirmware or stored in a memory accessible by the control device. Thecurrent ratio control curve can specify the current ratio of the firstcurrent provided to the first LED array 132 and the second currentprovided to the second LED array 134 as a function of at least thevariable reference signal.

The current ratio control curve can be provided in any suitable format.For instance, the current ratio control curve can be provided as a lookup table, matrix, correlation, or other data specifying the currentratio as a function of at least the variable reference signal. Thecurrent ratio control curve can be defined based on any desiredrelationship between the current ratio and the variable referencesignal. For instance, the current ratio control curve can be designed aslinear, super-linear, parabolic, logarithmic, asymptotic, exponential,as a step function, or other relationship between the current ratio andthe variable reference signal, depending on the desired performance ofthe lighting system.

FIGS. 2 and 3 depict example current ratio control curves according toexample aspects of the present disclosure. FIGS. 2 and 3 plot amagnitude of the variable reference signal along the horizontal axis, apercentage of maximum current that can be provided to the first LEDarray along the left vertical axis, and a percentage of maximum currentthat can be provided to the second LED array along the right verticalaxis.

FIG. 2 depicts three example current ratio control curves 302, 304, and306. Curve 302 depicts a current ratio control curve based on agenerally linear relationship. A current splitter circuit controllingthe current ratio according to curve 302 can linearly increase thecurrent supplied to the first LED array while linearly decreasing thecurrent supplied to the second LED array as the variable referencesignal is increased from about 0V to about 10V.

Curve 304 depicts an example control curve defined based on anexponential relationship. A current splitter circuit controlling thecurrent ratio according to curve 304 can exponentially increase thecurrent provided to the first LED array while exponentially decreasingthe current provided to the second LED array as the variable referencesignal is increased from about 0V to about 10V.

Curve 306 depicts an example control curve defined based on an inverseexponential relationship. A current splitter circuit controlling thecurrent ratio according to curve 306 can decrease the current providedto the first LED array while increasing the current provided to thesecond LED array as the variable reference signal is increased fromabout 0V to about 10V.

FIG. 3 depicts a current ratio control curve 308 defined based on a stepfunction. A current splitter circuit controlling the current ratioaccording to curve 308 can increase the current provided to the firstLED array in stepped incremental fashion while decreasing the currentprovided to the second LED array in stepped incremental fashion as thevariable reference signal is increased from about 0V to about 10V.

As demonstrated, a variety of possible current ratio control curves canbe defined for the current splitter circuit 120 of FIG. 1 depending onthe desired performance of the lighting system 100. This can beparticularly useful in circumstances where constant light levels aredesired between LED arrays associated with different color temperatureswhere one of the LED arrays operates at a different efficiency than theother LED arrays.

In embodiments where the first LED array 132 is associated with adifferent color temperature than the second LED array 134, theadjustment of the current ratio based on the variable reference signalcan provide for the independent adjustment of the color temperatureand/or other lighting effects of the lighting system 100. For instance,the dimmable driver circuit 110 can be controlled (e.g. using a dimmingcontrol signal) to simultaneously control the lumen output or dimming ofboth the first LED array 132 and the second LED array 134. The variablereference signal can be used to independently control the current ratiobetween the first current and the second current to adjust the colortemperature and/or other lighting effects of the overall light output bylighting system 100, irrespective of the driver output provided by thedimmable driver circuit 110.

FIG. 4 depicts a schematic of an example current splitter circuit 120according to example embodiments of the present disclosure. The currentsplitter circuit 120 receives the driver output from a driver circuitand couples the high voltage side of the driver output to the positiveterminals 212 of the LED arrays. The high voltage side of the driveroutput is provided to a regulator 220 (e.g. voltage regulator) whichregulates the driver output to an output level suitable for a controldevice 230. The high voltage side of the driver output can also be usedas Vin to power various components of the current splitter circuit 120.

The control device(s) 230 can include one or more suitable devices, suchas one or more microcontrollers, microprocessors, logic devices,integrated circuits, or other control devices. In particularimplementations, the control device(s) 230 can include timing circuitsconfigured to provide for programmable clock output and time stampoutput. The programmable clock output can be provided to control theplurality of LED arrays based on the clock output over a time period.For instance, the current splitter 120 can be configured toautomatically adjust a current ratio among a plurality of LED arrays atdifferent times throughout a day, month, or year to provide differentlighting effects based on the output of the timing circuits.

The control device(s) 230 can be coupled the negative terminals 214 ofthe LED arrays through various switching elements. For instance, thecontrol device 230 can be coupled to the negative terminal of the firstLED array via a first switching element 232. The control device 230 canbe coupled to the negative terminal of the second LED array via a secondswitching element 234.

The switching elements 232 and 234 illustrated in FIG. 4 are MOSFETdevices. However, those of ordinary skill in the art, using thedisclosures provided herein, will understand that other switchingelements (e.g. other types of transistors) can be used without deviatingfrom the scope of the present disclosure. The control device(s) 230 cancontrol the switching elements 232 and 234 by providing gate signals tothe switching elements 232 and 234.

According to particular aspects of the present disclosure, the controldevice(s) 230 can control the switching elements 232 and 234 based onthe variable reference signal from a second interface at the currentsplitter circuit 120. FIG. 5 depicts an example circuit 250 forproviding the variable reference signal to the current splitter circuit120. The circuit 250 can be internal or external to the current splittercircuit 120. For instance, the circuit 250 can be powered at least inpart by Vin provided from the current splitter circuit 120.

The circuit 250 can be coupled to a dimmer input 252 configured toreceive variable signal from a dimmer circuit, smart dimmer interface,potentiometer, Zener diode circuit, or other circuit. The circuit 250can provide a 0V to 10V variable reference signal at 254 based at leastin part on the signals received at the dimmer input 252. For example,the circuit 250 can provide the variable reference signal to the currentsplitter circuit 120 based at least in part on the signal received atthe dimmer input 252.

Referring back to FIG. 4, the control device(s) 230 can control theswitching elements 232 and 234 based on the variable reference signalaccording to a current ratio control curve 240 to provide a firstcurrent to the first LED array and a second current to the second LEDarray. The current ratio control curve 240 can be defined in firmware oras other instructions stored in a memory accessible by the controldevice(s) 230. The switching elements 232 and 234 can be controlled atan operating frequency that is selected to reduce the presence offlicker in the LED arrays as well as to reduce switching losses. Forinstance, in particular implementations, the switching elements 232 and234 can be operated at a frequency in the range of about 100 Hz to 1kHz.

According to particular aspects of the present disclosure, the switchingelements 232 and 234 can include inbuilt current sensing options (e.g.current sensing power MOSFETs) for purposes of overcurrent protection.More particularly, the switching element 232 can be configured toprovide a feedback signal via path 236 to control device 230 indicativeof a current flowing in switching element 232. Switching element 234 canbe configured to provide a feedback signal via path 238 to controldevice 230 indicative of a current flowing in switching element 234. Thefeedback signals can be used by the control device(s) 230 to provideovercurrent protection for the lighting system. For instance, thecontrol device(s) 230 can discontinue or modify operation of theswitching elements 232, 234 if the feedback signals from the switchingelements 232, 234 are indicative of excessive current flowing throughthe switching elements 232, 234.

FIGS. 6-8 depict additional example embodiments of lighting systemsaccording to example embodiments of the present disclosure. FIG. 6depicts a lighting system 102 that includes many similar elements to thelighting system 100 of FIG. 1. For instance, the lighting system 102includes a dimmable driver circuit 110, current splitter circuit 120,first interface 140, second interface, first LED array 132 and secondLED array 134.

In the example embodiment of FIG. 6, the driver circuit 110 and thecurrent splitter circuit 120 are both implemented as part of the LEDdriver module 115. For instance, driver circuit 110 and current splittercircuit 120 can be implemented on the same circuit board, in the samehousing, and/or using one or more common components. In this way, thecurrent splitter circuit 120 can be implemented within an LED drivermodule without requiring an external module disposed between an LEDdriver and the LED arrays.

The driver circuit 110 and the current splitter circuit 120 can receivea variable reference signal from an interface 140. The interface 140 canprovide a variable reference signal to the driver circuit 110 to controlthe driver output of the driver circuit 110 and can provide a variablereference signal to the current splitter circuit 120 to control thecurrent ratio among the plurality of LED arrays. The interface 140 caninclude one or more components for communicating the variable referencesignal to the driver circuit 110 and to the current splitter circuit120. For example, the interface 140 can include one or more circuits,terminals, pins, contacts, conductors, or other components forcommunicating a variable reference signal to the driver circuit and tothe current splitter circuit 120.

The variable reference signal can be provided from an external circuit,such as an external dimming circuit. The external circuit can includeone or more devices, such as a smart dimming interface, a potentiometer,a Zener diode, or other device. The interface 140 can include variouscircuits and/or control devices for selectively providing and adjustingthe variable reference signal to both the driver circuit 110 and thecurrent splitter circuit 120 to control dimming and/or other lightingeffects of the lighting system 100.

For instance, in one embodiment, a switch (e.g. a three-way switch),toggle, touch control, or the like can be implemented as part of theinterface 140 to select whether to adjust the variable reference signalto the driver circuit 110 and/or to the current splitter circuit 120. Inanother embodiment, a microcontroller or other control device can beused to recognize various user inputs at the interface 140. The userinputs can be interpreted to selectively adjust the variable referencesignal to the driver circuit 110 and/or the current splitter circuit120. For instance, the interface 140 can recognize that a user hasquickly provided a dimming input (e.g. manually adjusted a dimmercoupled to the interface 140) twice within a time period. The firstdimming input can be used to adjust the variable reference signal to thedriver circuit 110 and the second dimming input can be used to adjustthe variable reference signal to the current splitter circuit 120.

In yet another embodiment, an input device such as a 4-way joystickdimmer can be used to selectively control adjustment of the variablereference signal to the driver circuit 110 and/or the current splittercircuit 120. For instance, horizontal motion of the 4-way joystick canbe used to adjust the variable reference signal provided to the drivercircuit 110. Vertical motion of the 4-way joystick can be used to adjustthe variable reference signal provided to the current splitter circuit120. Diagonal motion of the 4-way joystick can be used to adjust thevariable reference signal to both the driver circuit 110 and the currentsplitter circuit 120.

Various other inputs and/or control devices for selectively controllingand adjusting the variable reference input to the driver circuit 110 andthe current splitter circuit 120 can be used without deviating from thescope of the present disclosure. For instance, a first interface can beused to provide a first variable reference signal to the driver circuit110 and a second interface can be used to provide a second variablereference signal to the current splitter circuit 120.

FIG. 7 depicts a lighting system 104 according to another exampleembodiment of the present disclosure. The lighting system 104 includes adriver circuit 110, a current splitter circuit 120 and a plurality ofLED arrays, including first LED array 132 and a second LED array 134. Inthe example embodiment of FIG. 7, both the dimming control interface 140and the interface 150 for receiving the variable reference signal areprovided at the current splitter circuit 120. As a result, the currentsplitter circuit 120 can provide a dual control interface that allowsfor dual control of both overall lumen output and color temperature orother lighting effects at the current splitter circuit.

More particularly, the dual control interface can receive a dimmingcontrol signal and a variable reference signal at the current splittercircuit 120. The dimming control signal and the variable referencesignal can be received from two separate or dual external circuits, suchas dimmer circuits, smart interface controls, potentiometers, Zenerdiode circuits, or other device. The dimming control signal can be usedto control the driver output. The variable reference signal can be usedto control the current ratio between the first LED array 132 and thesecond LED array 134 to provide different lighting effects.

FIG. 8 depicts a lighting system 106 according to another exampleembodiment of the present disclosure. FIG. 8 is similar to the lightingsystem 100 of FIG. 1, except that the lighting system 106 of FIG. 8additionally includes an optical sensor 160 in communication with thecurrent splitter circuit 120. The optical sensor 160 can be an ambientcolor sensor, light sensor, or other device configured to monitor lumenoutput and/or color of the light emitted by the LED arrays 132 and 134and/or the lighting system 106. The optical sensor can provide afeedback signal to the current splitter circuit 120. The feedback signalcan be indicative of the light output of the lighting system 106.

The current splitter circuit 120 can be configured to control thecurrent ratio based at least in part on the feedback signal. Forinstance, if the light output of the lighting system 106 varies from adesired light output as determined by, for instance, a current ratiocontrol curve or other control routine, the current splitter circuit 120can make adjustments to the current ratio to achieve the desired lightoutput.

FIG. 9 depicts a flow diagram of an example method (400) for controllinga plurality of LED arrays according to example embodiments of thepresent disclosure. The method (400) will be discussed with reference tothe lighting system 100 of FIG. 1 but can be implemented with othersuitable lighting systems. In addition, FIG. 9 depicts steps performedin a particular order for purposes of illustration and discussion. Thoseof ordinary skill in the art, using the disclosures provided herein,will understand that the steps of any of the methods disclosed hereincan be modified, adapted, expanded, omitted, and/or rearranged invarious ways without deviating from the scope of the present disclosure.

At (402), the method includes receiving an input power at a drivercircuit. For instance, the driver circuit 110 can receive an AC or DCinput power from a power source. At (404), the method includesconverting the input power to a driver output. For instance, the drivercircuit 110 can convert the input power into a suitable driver output(e.g. a 0V to 60V DC output). The driver output can be determined basedon the input power and/or based on dimming control signal.

At (406), the driver output is converted into a first current for afirst LED array and a second current for a second LED array. Forexample, the current splitter circuit 120 can convert the driver outputto a first current for the first LED array 132 and a second current forthe second LED array 134.

According to example aspects of the present disclosure, a current ratiobetween the first current and the second current can be determined basedat least in part on a variable reference signal received at the currentsplitter circuit. The variable reference signal can be received viainterface 150 provided at the current splitter circuit 120. The variablereference signal can be, for instance, a 0V to 10V lighting controlsignal or other suitable lighting control signal received from anexternal circuit, such as a dimmer circuit, smart interface control,potentiometer, Zener diode circuit, or other external circuit or device.

At (408), the method can include receiving an adjustment to the variablereference signal. For instance, the variable reference signal can beadjusted from 10V to 5V as a result of a user manually adjusting adimmer circuit providing the variable reference signal. In response tothe adjustment of the variable reference signal, the method can includeadjusting the current ratio between the first current and the secondcurrent (410). The current ratio between the first current and thesecond current can be adjusted according to a current ratio controlcurve. The current ratio control curve can specify the current ratiobetween the first current and the second current as a function of atleast the variable reference signal.

In this way, the light output of the lighting system can be controlledusing both a dimmable driver circuit and a variable reference signal.The dimmable driver circuit can be used to control the driver output tofacilitate increasing or reducing the overall lumen output of thelighting system. For instance, the method can include adjusting thedriver output based at least in part on a dimming control signal (412)to facilitate dimming of the first LED array and the second LED array.The variable reference signal can be used to control the current ratiobetween individual LED arrays in the lighting system, for instance, tofacilitate control of the color temperature of the overall light outputof the lighting system and/or to provide other lighting effects.

While the present subject matter has been described in detail withrespect to specific example embodiments thereof, it will be appreciatedthat those skilled in the art, upon attaining an understanding of theforegoing may readily produce alterations to, variations of, andequivalents to such embodiments. Accordingly, the scope of the presentdisclosure is by way of example rather than by way of limitation, andthe subject disclosure does not preclude inclusion of suchmodifications, variations and/or additions to the present subject matteras would be readily apparent to one of ordinary skill in the art.

1-20. (canceled)
 21. A current splitter circuit for a light emittingdiode (LED) system, comprising: an input configured to receive a drivercurrent; one or more outputs configured to provide a first current for afirst LED array and a second current for a second LED array according toa current ratio; an interface configured to receive a variable referencesignal for controlling the current ratio independently of the drivercurrent; wherein the current splitter circuit is configured to adjustthe current ratio of the first current and the second current accordingto a current ratio control curve, the current ratio control curvespecifying the current ratio between the first current and the secondcurrent as a function of at least the variable reference signal.
 22. Thecurrent splitter circuit of claim 21, wherein the current ratio controlcurve comprises a linear, super-linear, parabolic, logarithmic,asymptotic, or exponential relationship between the current ratio andthe variable reference signal
 23. The current splitter circuit of claim21, wherein the current ratio control curve comprises a step functiondefined at least in part on the variable reference signal.
 24. Thecurrent splitter circuit of claim 21, wherein the current splittercircuit comprises: a first switching element; a second switchingelement; and one or more control devices configured to control the firstswitching element to provide the first current to the first LED arrayand to control the second switching element to provide the secondcurrent to the second LED array.
 25. The current splitter circuit ofclaim 21, wherein the first switching element and the second switchingelement each comprise a current sensing MOSFET.
 26. The current splittercircuit of claim 21, wherein the interface is configured to receive thevariable reference signal from an external dimmer circuit.
 27. Thecurrent splitter circuit of claim 21, wherein the variable referencesignal is a 0V to 10V lighting control signal, a DALI lighting controlsignal, or a DMX lighting control signal.
 28. The current splittercircuit of claim 21, further comprising an optical sensor coupled to thecurrent splitter circuit, the optical sensor configured to provide afeedback signal indicative of a light output of the first LED array andthe second LED array to the current splitter circuit, the currentsplitter circuit configured to control the current ratio based at leastin part on the feedback signal.
 29. The current splitter circuit ofclaim 21, wherein the first LED array is associated with a differentcolor temperature than the second LED array such that adjustment of thevariable reference signal facilitates adjustment of the colortemperature of the LED system.
 30. The current splitter circuit of claim21, wherein the current splitter circuit comprises a timing circuit, thetiming circuit configured to provide a clock output, the currentsplitter circuit configured to adjust the current ratio of the firstcurrent and the second current based at least in part on the clockoutput to provide different lighting outputs at different times.
 31. Amethod for controlling a light emitting diode (LED) system, the methodcomprising: receiving an input power at a dimmable LED driver circuit;converting, by the dimmable LED driver circuit, the input power to adriver current; splitting, with a current splitter circuit, the drivercurrent into a first current for a first LED array and a second currentfor a second LED array according to a current ratio; receiving, at thecurrent splitter circuit, a clock output from a timing circuit; andadjusting, by the current splitter circuit, a current ratio between thefirst current and the second current based at least in part on the clockoutput.
 32. The method of claim 31, wherein the first LED array isassociated with a different color temperature than the second LED arraysuch that adjustment of the current ratio provides light output ofdifferent color temperatures at different times.
 33. A light emittingdiode (LED) system, the LED system comprising: a first LED array havingone or more LED devices; a second LED array having one or more LEDdevices, a driver module, the driver module comprising a dimmable drivercircuit and a current splitter circuit, the dimmable driver circuitconfigured to provide a driver current, the current splitter circuitconfigured to split the driver current into a first current for thefirst LED array and a second current for the second LED array accordingto a current ratio; wherein the driver module has an interfaceconfigured to receive a variable reference signal for controlling thecurrent ratio independently of the dimmable driver circuit, the currentsplitter circuit comprising one or more control devices configured toadjust the current ratio of the first current and the second currentindependently of the driver current according to a current ratio controlcurve, the current ratio control curve specifying the current ratiobetween the first current and the second current as a function of atleast the variable reference signal.
 34. The LED system of claim 33,wherein the dimmable driver circuit and the current splitter circuit areimplemented on the same circuit board.
 35. The LED system of claim 33,wherein the current ratio control curve comprises a linear,super-linear, parabolic, logarithmic, asymptotic, or exponentialrelationship between the current ratio and the variable reference signal36. The LED system of claim 33, wherein the current ratio control curvecomprises a step function defined at least in part on the variablereference signal.
 37. The LED system of claim 33, wherein the currentsplitter circuit comprises: a first switching element; a secondswitching element; and wherein the one or more control devices areconfigured to control the first switching element to provide the firstcurrent to the first LED array and to control the second switchingelement to provide the second current to the second LED array.
 38. TheLED system of claim 33, wherein the dimmable driver circuit comprises aline dimming driver.
 39. The LED system of claim 33, wherein the drivermodule comprises an interface configured to receive a dimming controlsignal, the driver current being dependent on the dimming controlsignal.
 40. The LED system of claim 33, wherein the driver modulecomprises a timing circuit, the timing circuit configured to provide aclock output, the current splitter circuit configured to adjust thecurrent ratio of the first current and the second current based at leastin part on the clock output to provide different lighting outputs atdifferent times.